It is generally known to actuate electric three-phase current machines by means of a power inverter which is supplied with electrical energy by a direct current source and which converts the direct voltage into an alternating voltage by means of a multiplicity of power switches, and as a result supplies the electric machine with electrical energy or with electric current. The power switches are actuated or switched here in accordance with the electrical frequency of the machine, and therefore in accordance with the rotational speed. In the starting mode of the electric machine, large currents usually flow through the actuated phase sections, and due to the low electrical frequency at low rotational speeds the corresponding power switches are loaded by the corresponding phase current over a relatively long time period. This high loading can damage the power switches of the power inverter, with the result that measures have to be taken to limit the loading of the power switches.
In conventional methods, when the load limit of the power switches is reached, the power is decreased in order to limit the loading of the power switches and avoid damage to the power switches. This abrupt reduction in the torque which is made available is uncomfortable and can give rise to situations which are critical for safety when the method is applied in a motor vehicle, since the desired or requested power is unexpectedly not made available. As a result of the abrupt reduction in the torque which is made available, the drive train is abruptly relieved of tension, as a result of which oscillations which additionally have a very adverse effect on the driving comfort can occur in the drive train.